Process and device for the generation of high electric voltages



Nov. 23, 1954 w, J, VAN K 2,695,367

PROCESS AND DEVICE FOR THE GENERATION OF HIGH ELECTRIC VOLTAGES FiledNOV. 1, 1951 (INsuLATE0) COOL/N6 MEANS 2 FIGJ F|6.2

United States Patent ()fiice PROCESS AND DEVICE FOR THE GENERATION OFHIGH ELECTRIC VOLTAGES Willem Johannes Dominicus van Dijck, The Hague,Netherlands, assignor of one-half to Stichting voor FundamenteelGnderzoek der Materie, Utrecht, Netherlands, a corporation of theNetherlands Application November 1, 1951, Serial No. 254,246

Claims priority, application Netherlands November 2, 1950 21 Claims.(Cl. 310-) The invention relates to a process for the generation of highelectric voltages and to a device for application of this process.

High direct voltages, more or less constant, have been generated bycharging a spherical body, insulated from earth, by blowing fineparticles of infusorial-earth into said spherical body by means ofcompressed air. These particles first pass through a narrow copper tubein which they are charged by friction; thereupon they pass through along glass insulated tube and finally give ofi their charge to smallcopper tubes within the sphere. Through another glass tube the dustparticles fall back into the reservoir. The reliability of such adevice, however, is not very good.

Another conventional method of generating high electric voltages is bythe local forming of space charges in an insulating liquid, andsubsequently passing this liquid to a device, such as a metal vessel, towhich the space charges may be given off.

When the liquid has passed this device, said liquid is preferablyreturned to the place where the space charge is generated.

The present, invention is based upon the realization that the highvoltages which occasionally are accidentally observed it insulatingliquids (such as kerosene) are pumped into. a tank, are the result ofso-called streaming potentials. These streaming potentials arewell-known for aqueous solutions, in which they are caused by smallquantities of ionizable substances, the differently charged parts ofwhich are adsorbed in different ways by the wall of the tube. At aproper value of the concentration, the least strongly adsorbed part willbe partly carried olf by the liquid. Whereas with aqueous solutionsmerely low voltages can be generated, very high voltages may be obtainedwith insulating liquids by this process.

According to the invention a space. charge is generated in an,insulating liquid based on the above-mentioned principle of streamingpotentials, by using a liquid containing a quantity of an ionizablesubstance, the variously charged ions of which are adsorbed in diiferentdegrees by metal and by passing this liquid along a metal, e. g. asystem of metal tubes or slits, at which process at least part of thenot or less strongly adsorbed ions are carried off by said insulatingliquid.

The concentration of the ionizable substance in the insulating liquidis, preferably adjusted in such a way that a maximal effect (with regardto the voltage to be obtained and/or the strength of current to be givenoff) is attained. If necessary a quantity of this substance mayconstantly or intermittently be added to the insulating liquid.

The strength of current to be generated is dependent on the velocity offlow along the wall, so that itis necessary to increase this velocity asmuch as possible, and preferably to work with a strong turbulent flow.Viz. in this latter case the charge which is carried along close to thewall, will spread through the liquid as a space charge.

By the electrical conductivity of the liquid and its dielectricconstant, a half life value may be definedthat is to say the time inwhich half the charge of this liquid flows to the wall. When a liquid,charged in this way, is brought into a metal vessel, the charge willgradual ly flow towards the wall of the vessel, i. e. after one2,695,367 Patented Nov. 23, 1954 half life, the liquid will only havehalf the original charge left, and after twice the time of a half life,A of the original charge will be left, etc.

In connection herewith the velocity of flow is chosen so that, duringthe process in question, the time elapsing between the generation of thespace charge in a certain part of the liquid and its reaching theabove-mentioned device, to which the charge is communicated is smallwhen compared to the afore-mentioned half-life. Moreover care should betaken, e. g. by the selection of suitable dimensions of the device towhich the charge is given off, during which the average time that acertain part of the liquid remains in said device, is large whencompared to the time of average half-life.

The liquid, which has given off the greater part of its charge to thewall of the above-mentioned device may thereupon be returned to themetal tubes or slits via an insulating tube of adequate length. Apumping device has to be put into the circuit to effect the flow of theliquid. In this Way a large diiference of potential may be generatedbetween the wall of the device and the wall of the metal slits or tubes.

The invention will be further explained with the help of the annexeddrawings.

Fig. 1 is a schematical view of an apparatus, which is particularlysuitable for the execution of the process according to the invention.

Fig. 2 is a schematic view of a second embodiment of apparatusincorporating the principles of the present invention showing means forobtaining still higher voltages by combining two apparatus in series.

Through a centrifugal pump 1 an insulating liquid, e. g. gasoline orkerosene or a pure hydrocarbon of low viscosity is forced through apacket of metal plates 2, preferably of iron, which are mounted at asmall distance from each other (e. g. 1 mm.); the lengthy of the platesin the direction of the flow amounts to about 5l0 times this distance,so that the turbulence may develop well. In general the length of thispart of the apparatus must be about 3-5 times the hydraulic radius. Goodresults were obtained when this metal part was constructed as a diskwith a length of 8 mm., provided with 200 vertical cylindrical holeswith a diameter of 1 mm., and a quantity of 5000 liters of insulatingliquid/hour was forced through these holes. The system of metal platesis connected to earth. Thereafter the liquid flows through an insulatingtube 3 to a metal storage vessel 4, preferably a copper vessel, which isinsulated. When used in combination with the aforementioned disk thediameter of these tubes has to be about 35-40 mm. with a length of about1.5 meters. In order to avoid undesired turbulences in this storagevessel, the liquid flows first through a metal Venturi-tube 5. In thisvessel the liquid will move approximately along the lines of flowindicated by the dotted lines, at the same time giving off its charge tothe wall of the vessel. From here, the liquid is sucked otf via aninsulating tube 6 and returned to the suction side of the centrifugalpump 1. In order to remove the heat which is generated by friction, acooling device 7 may, if necessary, be put into the circuit, preferablybetween the pump 1 and the metal plates 2.

Preferably an organic liquid of low viscosity is used as an insulatingliquid, such as hydrocarbons, gasoline and kerosene, as otherwise toomuch energy is required to circulate the liquid. Also halogenatedhydrocarbons and carbon disulfide may be applied, the advantage thereofbeing less danger of an arcing discharge in the gaseous state than whenhydrocarbons are used.

Various soaps and soapy substances such as sulphonates have proved to bevery suitable as ionizable substances with various degrees ofadsorption. The optimal concentrations are between 0.001 and 0.1%. Verygood results were obtained with a liquid, consisting of gasoline I. P.,containing 0.01% by weight of magnesiumsulphonate. Used in combinationwith the described apparatus having a disk with 200 holes, a voltage of50,000 volts could be generated, when a current of 0.5 amp. was takenoff. A suitable half life is about 5 seconds. This half life may beadjusted by changing the conductivity which may be strongly increased bythe addition of bituminous substances. The distance from the plates 2 tothe storage vessel 4 will depend on the desired voltage, but willusually amount to several meters. In consequence thereof, the velocityof flow in the tubes 3 and 6 must be in the neighborhood of to 10 m. persecond, to traverse the distance from point 2 to point 4 in a time whichis short compared to the half life. The dimensions of the vessel 4 mustbe chosen so that the time during which the liquid remains within thevessel amounts to at least 35 times the half life. The minimum radiusfor the case where the vessel is a sphere, is also determined on thebasis of electrical considerations, by the requ rement that no sprayingefiects may occur. In combination with the aforementioned disk with 200holes, a sphere was used with a radius of about 18 cm. The apparatusmust be provided with means for filling and de-aerat- It is notnecessarythat the device 2 be connected to earth or that the storagevessel 4 be insulated. The device 2 or the vessel 4 need only beconnected to some reference potential source of sufiicient capacity.

In principle the process may also be carried out 1n reverse, as long asthe device 2 is constructed in a suitable way, e. g. that it is mountedwithin an insulated hollow metal sphere of adequate dimensions, and thatthe metal slits are electrically connected with the sphere.

A number of circuits may be put in series in order to obtain a highervoltage. In Figure 2 is schematically indicated how a double voltagecould be generated by means of two circuits. Both circuits are served bythe pump 1. If the storage vessel 4 which is insulated, is chargedpositively when compared to the device 2, the insulated device 2 will becharged negatively when compared to the storage vessel 4. Device 2 andthe storage vessel 4 are connected to earth.

The high voltage now occurs between the device 2 and the storage vessel4.

I claim:

1. Apparatus for generating high electrical voltages, comprising, incombination, a liquid conveying means arranged in a closed path forcirculating a liquid; an insulating liquid carrying an ionizablesubstance located in said liquid conveying means; means for generating aspace charge mounted in a first portion of said conveying means andconstructed as a grounded metallic member to be contacted by the liquidpassing therethrough thereby producing a space charge in the liquid as aresult of the selective adsorption of ions present in the liquid by saidmetallic member; a conductive vessel located at a second part of saidliquid conveying means spaced from said first part thereof, foraccumulating the charge produced in the liquid at said first part ofsaid liquid conveying means, said conductive vesel forming part of saidliquid conveying means; and insulating means located between said meansfor generating a space charge and said conductive vessel for insulatingthe same from each other, said insulating means forming part of saidliquid conveying means.

2. Apparatus for generating high electrical voltages comprising, incombination, a liquid conveying means arranged in a closed path forcirculating a liquid; an insulating liquid carrying an ionizablesubstance and a bituminous product located in said liquid conveyingmeans; means for generating a space charge mounted in a first portion ofsaid conveying means and constructed as a grounded metallic member to becontacted by the liquid passing therethrough thereby producing a spacecharge in the liquid as a result of the selective adsorption of ionspresent in the liquid by said metallic member; a conductive vessellocated at a second part of said liquid conveying means spaced from saidfirst part thereof, for accumulating the charge produced in the liquidat said first part of said liquid conveying means, said conductivevessel forming part of said liquid conveying means; and insulating meanslocated between said means for generating a space charge and saidconductive vessel for insulating the same from each other, saidinsulating means forming part of said liquid conveying means.

3. Apparatus for generating high electrical voltages comprising, incombination, a liquid conveying means arranged in a closed path forcirculating a liquid; an insulating liquid having a soap dissolvedtherein located in said liquid conveying means; means for generating aspace charge mounted in a first portion of said conveying means andconstructed as a grounded metallic member to be contacted by the liquidpassing therethrough thereby producing a space charge in the liquid as aresult of the selective adsorption of ions present in the liquid by saidmetallic member; a conductive vessel located at a second part of saidliquid conveying means spaced from said first part thereof, foraccumulating the charge produced in the liquid at said first part ofsaid liquid conveying means, said conductive vessel forming part of saidliquid conveying means; and insulating means located between said meansfor generating a space charge and said conductive vessel for insulatingthe same from each other, said insulating means forming part of saidliquid conveying means.

4. Apparatus for generating high electrical voltages comprising, incombination, a liquid conveying means arranged in a closed path forcirculating a liquid; an insulating liquid carrying an ionizablesubstance, said ionizable substance being 0.00l0.1% of the liquidvolume, said liquid located in said liquid conveying means; means forgenerating a space charge mounted in a first portion of said conveyingmeans and constructed as a grounded metallic member to be contacted bythe liquid passing therethrough thereby producing a space charge in theliquid as a result of the selective adsorption of ions present in theliquid by said metallic member; a conductive vessel located at a secondpart of said liquid conveying means spaced from said first part thereof,for accumulating the charge produced in the liquid and said first partof said liquid conveying means, said conductive vessel forming part ofsaid liquid conveying means; and insulating means located between saidmeans for generating a space charge and said conductive vessel forinsulating the same from each other, said insulating means forming partof said liquid conveying means.

5. Apparatus for generating high electrical voltages comprising, incombination, a liquid conveying means arranged in a closed path forcirculating a liquid; an insulating liquid carrying an ionizablesubstance consisting of at least one sulphonate located in said liquidconveying means; a source of reference potential; means for generating aspace charge mounted in a first portion of said conveying means andconstructed as a metallic member connected to said source of referencepotential to be contacted by the liquid passing therethrough therebyproducing a space charge in the liquid as a result-of the selectiveadsorption of ions present in the liquid by said metallic member; aconductive vessel located at a second part of said liquid conveyingmeans spaced from said first part thereof, for accumulating the chargeproduced in the liquid at said first part of said liquid conveyingmeans, said conductive vessel forming part of said liquid conveyingmeans; and insulating means located between said means for generating aspace charge and said conductive vessel for insulating the same fromeach' other, said insulating means forming part of said liquid conveyingmeans.

6. Apparatus for generating high electrical voltages comprising, incombination, a liquid conveying means arranged in a closed path forcirculating a liquid; an insulating liquid carrying an ionizablesubstance and having a high resistance against breaking down in thegaseous state, located in said liquid conveying means; means forgenerating a space charge mounted in a first portion of said conveyingmeans and constructed as a grounded metallic member to be contacted bythe liquid passing therethrough thereby producing a space charge in theliquid as a result of the selective adsorption of ions present in theliquid by said metallic member; a conductive vessel located at a secondpart of said liquid conveying means spaced from said first part thereof,for accumulating the charge produced in the liquid at said first part ofsaid liquid conveying means said conductive vessel forming part of saidliquid conveying means; and insulating means located between said meansfor generating a space charge and said conductive vessel for insulatingthe same from each other, said insulating means forming part of saidliquid conveying means.

7. Apparatus for generating high electrical voltages comprising, incombination, a liquid conveying means arranged in a closed path forcirculating a liquid; an insulating liquid having a high resistanceagainst breakdown and having therein a halogenated hydrocarbon of lowviscosity and carrying an ionizable substance, located in said liquidconveying means; means for generating a space charge mounted in a firstportion of said conveying means and constructed as a grounded metallicmember to be contacted by: the liquid passing therethrough therebyproducing a. space chargev in the. liqu d: as a result of the selectiveadsorption of" ions present in the liquid by said metallic member; aconductive vessel located at asecond part of said liquid" conveyingmeans spaced from said firstpart thereof; for accumulatmg the chargeproduced in the liquid: at said? first part of said liquidconveyingmeans, said conductive vessel forming part of said liquid conveyingmeans; and. insulating means located between said means for generating aspace charge and said conductive vessel forinsulating the same from eachother said insulating means forming part of said liquid conveying means.

8'. Apparatus for generating high electrical voltages comprising, incombination, a liquid conveying rneans arranged in a closed path forcirculating a liquid; an insulating liquid carrying an ionizablesubstance located in said conveying means; means for generating; a spacecharge mounted" in a-firstportion of said conveymgmeans and constructedas grounded narrow metallic tubes to be contacted by the liquid passingtherethrough thereby producing a space charge in the liquid as a res ultof the selective adsorption of ions; present in the liquid by saidmetallic tubes; a conductive vessel located at a second part of saidliquid conveying means, spaced from said first part thereof, foraccumulating the charge produced in the liquid at said first part ofsaid liquid conyeymg means, said conductive vessel forming part of said;liquid' conveying means;- and insulating means located between saidmeans for generating a space charge and said conductive vessel forinsulating the same from each other, said insulating means forming; partof said liquidconveying. means.

9.. Apparatus; for generating high electrical voltages comprising, incombination, aliquid conveying means arranged. in a closed path forcirculating a liquid; an 1nsulating liquid carryingan ionizablesubstance located in said liquid conveying means; means for generating aspace charge mounted in a first portion of said conveying means andconstructed asgrounded narrow metallic tubes spaced approximately 1 mm.apart, the height of said tubes in the direction of liquid flow being approximately 510 mm. to be contacted by the liquid passing therethroughthereby producing a space charge in the liquid as a result oi theselective adsorption of ions present in the liquid by said metallictubes; a conductive vessel located at a second part of said liquidconveying means, spaced from said first part thereof, for accumulating;the, charge. produced in the, liquid at said first part of said. liquidconveying means, said conductive vessel forming part of said liquidconveying means; and insulating meansw located between said means forgenerating a space charge and said conductive vessel for insulating thesame from each other, said insulating means forming part of said liquidconveying means.

10. Apparatus for generating high electrical voltages comprising, incombination, a liquid conveying means arranged in a closed path forcirculating a liquid; an insulating liquid carrying an ionizablesubstance located in said liquid conveying means; means for generatinga, space charge mounted in a first portion of said conveying means andconstructed as grounded metallic slits to be contacted by the liquidpassing therethrough thereby producing a space charge in the liquid as aresult of the selective adsorption of ions present in the liquid by saidmetallic slits; a conductive vessel located at a second part of saidliquid conveying means, spaced from said first part thereof, foraccumulating the charge produced in the liquid at said first part ofsaid liquid conveying means; and insulating means located between saidmeans for generating a space charge and said conductive vessel forinsulating the same from each other, said conductive vessel forming partof said liquid conveying means.

11. Apparatus for generating high electrical voltages comprising, incombination, a liquid conveying means arranged in a closed path forcirculating a liquid; an insulating liquid carrying an ionizablesubstance located in said liquid conveying means; means for generating aspace charge mounted in a first portion of said conveying means andconstructed as a grounded metallic member having a large wall surface tobe contacted by the liquid passing therethrough thereby producing aspace charge in the liquid as a result of the selective adsorption ofions present in the liquid by said metallic member; a

- arranged in a closed conductive vessel located at av second: part ofsaid liquid;

ductive vessel forming part of said liquid conveying means; andinsulating means located between said; means for generating a spacecharge and said conductive vessel for insulating the same. from eachother, said insulating means forming part of said liquid conveyingmeans.

12.. Apparatus for generating high electrical voltages comprising, incombination, a liquid. conveying means arranged in a closed path forcirculating a liquid; an insulating liquid carrying an ionizablesubstance located in said liquid conveying means; means for circulatinga liq.- uid through said conveying means in a turbulent motion, saidcirculating means forming part of said liquid conveying means; means forgenerating a space charge mounted in a first portion of said: conveyingmeans and constructed as a grounded metallic member to be contacted bythe liquid passing therethrough thereby producing a space charge in theliquid as a result of the selective adsorption ofions present in theliquid by said metallic member; a conductive vessel located at a secondpart of said liquid conveying means, spaced from said first partthereof, foraccumulating the charge produced in the liquid atsaid firstpart of said liquid conveying means, said conductive vessel formingpartof said liquid conveying means; and insulating means located betweensaid means for generating a space charge and said conductive vessel forinsulating the same from each other, said insulating: means form-ingpart of said liquid convey-ing means.

13-. Apparatus for generating high electrical voltages comprising, incombination, a liquid conveying means arranged in a closed path forcirculating a liquid; an insulating liquid carrying an ionizablesubstance located in said liquid conveying means; means forgenerating aspace charge mounted in a first portion of said conveying means andconstructed as a grounded metallic memher to. be contacted by the liquidpassing therethrough thereby producing a space charge in' the liquid asa result of the selective adsorption of ions present in the liquid bysaid metallic member; a conductive sphere located at a second part ofsaid liquid conveying means, spaced from said first part thereof, foraccumulating the charge produced in the liquid at said first part ofsaid liquid conveying means, said conductive sphere forming part of saidliquid conveying means; and insulating means located between saidmeansfor generating a space charge and said conductive sphere forinsulatng the same from each other, said insulating means forming partof said liquid conveying means.

14'. Apparatus for generating high electrical voltages comprising, incombination, a liquid conveying means path for circulating a liquid; aninsulating liquid carrying an ionizable substance located in said liquidconveying means; means for generating a space charge mounted in a firstportion of said conveying means and constructed as a grounded metallicmember to be contacted by the liquid passing therethrough therebyproducing a space charge in the liquid as a result of the selectiveadsorption of ions present in the liquid by said metallic member; ametal vessel located at a second part of said liquid conveying means,spaced from said first part thereof, for accumulating the chargeproduced in the liquid at said first part of said liquid conveyingmeans, said metal vessel forming part of said liquid conveying means;and insulating means located between said means for generating a spacecharge and said metal vessel for insulating the same from each other,said insulating means forming part of said liquid conveying means.

15. Apparatus for generating high electrical voltages comprising, incombination, a liquid conveying means arranged in a closed path forcirculating a liquid; an insulating liquid carrying an ionizablesubstance located in said liquid conveying means; means for generating aspace charge mounted in a first portion of said conveying means andconstructed as a grounded metallic member to be contacted by the liquidpassing therethrough thereby producing a space charge in the liquid as aresult of the selective adsorption of ions present in the liquid by saidmetallic member; a conductive vessel located at a second part of saidliquid conveying means, spaced from said first part thereof, foraccumulating the charge produced in the liquid at said first part ofsaid liquid conveying means, said conductive vessel forming part of saidliquid conveying means; and insulating means located between said meansfor generating a space charge and said conductive vessel for insulatingthe same from each other, said insulating means forming part of saidliquid conveying means and having a length such that the time whichlapses between the generation of the space charge in the liquid and itsaccumulating on said conductive vessel is short compared to thehalf-life of the charge.

16. Apparatus for generating high electrical voltages comprising, incombination, a liquid conveying means arranged in a closed path forcirculating a liquid; an insulating liquid carrying an ionizablesubstance located in said liquid conveying means; means for generating aspace charge mounted in a first portion of said conveying means andconstructed as a grounded metallic member to be contacted by the liquidpassing therethrough thereby producing a space charge in the liquid as aresult of the selective adsorption of ions present in the liquid by saidmetallic member; a conductive vessel located at a second part of saidliquid conveying means spaced from said first part thereof, foraccumulating the charge produced in the liquid at said first part ofsaid liquid conveying means, said conductive vessel forming part of saidliquid conveying means; and insulating means located between said meansfor generating a space charge and said conductive vessel for insulatingthe same from each other, said insulating means forming part of saidliquid conveying means, and having a diameter of 35-40 mm. and a lengthof about 1.5 meters.

17. Apparatus for generating high electrical voltages comprising, incombination, a liquid conveying means arranged in a closed path forcirculating a liquid; an insulating liquid carrying an ionizablesubstance located in said liquid conveying means; means for generating aspace charge mounted in a first portion of said conveying means andconstructed as a grounded metallic member to be contacted by the liquidpassing therethrough thereby producing a space charge in the liquid as aresult of the selective adsorption of ions present in the liquid by saidmetallic member; a conductive vessel located at a second part of saidliquid conveying means, spaced from said first part thereof, foraccumulating the charge produced in the liquid at said first part ofsaid liquid conveying means, said conductive vessel forming part of saidliquid conveying means; and insulating means located between said meansfor generating a space charge and said conductive vessel for insulatingthe same from each other, said insulating means forming part of saidliquid conveying means; and cooling means connected to said liquidconveying means for cooling the liquid flowing therethrough.

18. Apparatus for generating an electrostatic potential comprising, incombination, conduit means; an insulating liquid having an ionizablesubstance dissolved therein located in said conduit means; meansoperatively associated with said conduit means for circulating saidinsulating liquid through said conduit means; a source of referencepotential; conductive space charge generating means mounted in a firstportion of said conduit means 8 and in contact with said insulatingliquid for producing a space charge in said insulating liquid byselectively adsorbing therefrom a portion of the ions present in saidinsulating liquid, said space charge generating means being connected tosaid source of reference potential;

means has a length such that the time which lapses be-' tween thegeneration of the space charge in said insulating liquid and itsaccumulating on said conductive vessel means is short compared to thehalf life of said charge.

20. A process for generating an electrostatic potential comprising thesteps of producing a space charge in an insulating liquid having anionizable substance therein by selectively adsorbing therefrom a portionof the ions therein; passing the charged liquid through an insulatingconduit at a speed sufficient so that only a minor part of said spacecharge is lost during the passage of said liquid through said insulatingconduit; and collecting from the liquid after it has passed through saidinsulating conduit the charge therein.

21. A process of generating an electrostatic potential comprising thesteps of producing a space charge in an insulating liquid having anionizable substance therein by selectively adsorbing therefrom a portionof the ions therein; passing the charged liquid through an insulatingconduit at a speed sufficient so that only a minor part of said spacecharge is lost during the passage of said liquid through said insulatingconduit; collecting from the liquid after it has passed through saidinsulating conduit the charge therein; cooling the liquid after thecharge has been collected therefrom; and continuously repeating all ofthe preceding steps in the order named.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 2,078,760 Hansell Apr. 27, 1937 2,208,217 Landerholm July 16,1940 2,308,884 Lindenblad Jan. 19, 1943 2,572,765 Roudaut Oct. 23, 19512,577,542 Roudaut Dec. 4, 1951 FOREIGN PATENTS Number Country Date812,996 France Feb. 15, 1937 OTHER REFERENCES ggysical Review, vol. 42,pp. 298-304, October 15,

